Advertisements The corporations wouldn't be using Fish, etc. as "experts" per say (although those firms would likely hire expert witnesses). Rather, most corporations hire such firms as outside counsel to actually litigate the entire case. In most instances, in-house counsel would only make final strategic calls and monitor the outside firm to make sure they're handling the case effectively and satisfactorily. I'd guess that given the Tivo patent's history, AT&T and Verizon are more likely to rely on non-infringement defenses instead of invalidity.